The present invention relates in general to belt conveyors, and more particularly to idler rollers for conveyor belts.
Conveyor belts are widely used for transporting a variety of materials, e.g. sand, gravel, from one location to another. Such conveyor belts include not only flat bed conveyor belts, but also conveyor belts having a troughed configuration for improved retention of transported material. Conveyor belts typically run on a system of idler rollers with rotational power provided by a primer mover. Since the idler rollers associated with such conveyor belts experience considerable use, attention has been given to improving their reliability.
Idler rollers used with conveyor belts are typically exposed not only to continuous friction due to motion of the conveyor belt, but also to a wide variety of foreign matter. The foreign matter frequently presents serious wear problems to the moving surfaces associated with the idler rollers. Such foreign matter originates from a wide variety of sources and frequently originates from materials carried by the conveyor belt, e.g., sand, gravel, et cetera. Such materials have the potential of not only reducing the effect of lubricants employed to neutralize friction in idler roller assemblies, but also may cut and abrade associated bearing surfaces. As a result of such abrasive action, idler rollers are frequently replaced.
In addition to the foregoing, uneven distribution of load material on the conveyor belt may result in relative movement of an idler roller. Such relative movement not only acts to introduce additional wear on load bearing surfaces, but also causes axial displacement of the idler roller relative to the support shaft about which rotation occurs. This frequently not only disturbs the operation of the conveyor belt, but further impacts other related processes which rely on an uninterrupted operation of the conveyor belt.
The U.S. Pat. No. 666,164 to Titus, issued on Jan. 15, 1901, for Roller Mechanism For Conveyor Belts, discloses a pair of inclined laterally-extended tubular rollers, held in position at a lower end by a circumferential rib and an associated collar, and at an upper end by a shoulder and associated shoulder cap. Lubrication may be introduced into the assembly through an associated funnel arrangement.
The U.S. Pat. No. 858,612 to Mason, issued on July 2, 1907, for Rollers For Belt Conveyors, discloses the use of lateral-extended tubular rollers, inclined or projected in a direction transverse to the direction of travel of the conveyor belt to form a trough roller assembly.
The U.S. Pat. No. 3,648,824 to Speck, issued on Mar. 14, 1972, for Idler Roller Device For Troughed Conveyor Belts, discloses an arrangement for the reduction of friction through the use of a smooth bearing surface of a metal construction engaging a urethane surface. The patent to Speck further discloses an axial thrust bearing, e.g., a spherical ball bearing, disposed between an upper end of a roller and a support shaft. A pair of idler rollers are mounted on an upwardly and rearwardly inclined support shaft to exert a downward thrust to maintain the rollers on the support shaft.
The U.S. Pat. No. 4,266,662 to Reid, issued on May 12, 1981, for Trough Roller Assembly, discloses a radially projecting shoulder at the distal end of a support shaft, and an interfitting groove to prevent axial movement of the idler roller with respect to the support shaft.
Heretofore external keeper seals were employed in conjunction with idler rollers disposed for supporting conveyor belts having a troughed configuration. The purpose of the external keeper seals was to inhibit the penetration of moisture and dirt in the area between the shaft and the axial opening of the idler roller.